Machine for grinding bevel gears



June 1, 1948. M. J. SUIRE 2,442,734

MACHINE FOR GRINDING BEVEL GEARS Filed Jan. 9, 1946 4Sheets-Sheet 1 CUM June 1, 1948. M'. J. SUIRE MACHINE FOB. GRINDING BEVEL GEARS 4 sh9ets s 2 Filed 1946 June 1, 1948. M. J. sums ,7

MACHINE FOR GRINDING BEVEL GEARS Filed Jan. 9,, 1946 '4 Sheets-Sheet 3 June 1, 1948. I su 2,442,734

\ MACHINE FOR GRINDING BEVEL GEARS Filed Jan. 9, 1946 4 Sheets-Sheet 4 I/vvc NTOR 8, (43%, M I T Patented .Fnne 1, 19 .18

STATES PATENT OFFICE Application January 9, 1946, Serial No. 640,065 In France January 30, 1945 Claims.

It has already been proposed to cut or to grind bevel gears by guiding the tool over the side of the gear tooth, homothetically with reference to a gauge reproducing at a larger scale the desired outline. Each tooth of the gear comes in its turn in front of the tool and the shape of this tool, once cut or ground, is that of the elementary conical surface the apex of which is the center of homothetical projection and the base is the gauge used. The usual technique of these machines is similar to that of reproducing machines. The gauge is stationary and a feeler passes over its outline while the tool rigid with said feeler describes or encloses the homothetic surface formed by the tooth. Reversely it has also been proposed to make the gauge and the work rotate round an axis passing through a stationary point while the tooth and the feeler remain stationary.

Although simple in its principle, this method shows however the drawback of requiring in its application an intricate mechanism for the cooperation between the different movements of the tool and of the work as well as for the rotary drive of this tool.

My invention has for its object a method for rectifying the sides of bevel gear teeth, according to which the tool on one hand and the gear tooth on the other both assume a simple rocking movement round an axis, the two movements being suitably associated.

According to my invention, the rocking movement of the gear wheel to be ground and consequently that of the tooth is controlled by the rocking movement of the tool through the agency of positive connecting means constituted advantageously by a cam the outline of which is a homothetic amplification of the outline of the desired tooth.

A simple form of execution of this connection is obtained by constraining a rocking plane associated with the tool to remain tangent to the side of the cam which latter is mounted after the manner of a pendulum round an axis perpendicular to the axis of oscillation of said rocking plane and meeting said axis.

This rocking plane contains thus permanently a generating line of the cone the apex of which lies at the meeting point of the two rocking axes and the base of which forms the control cam. During the rolling movement of the plane over the cam, all the generating lines of said cone included between the extreme points of tangency enter in succession the plane enclosing in its difierent positions this conical surface element. Consequently, it is easy to ,form the cutting plane for the tool in the rocking plane, the edge of this cutting plane which is generally circular, being tangent to the rocking shaft while the gear is mounted in a manner such that each of its teeth engages in succession a position such that the enveloped cone elements coincide with the side of the tooth to be ground; but obviously the cooperation being thus obtained, the two movements may be used indirectly for controlling the movement of the tool on one hand and the work to be ground on the other.

In the grinding operation, the tool is generally a grinding wheel.

In order to ensure for this grinding wheel a constant outline, whatever its wear may be, and to keep this outline in a suitable position i. e. with its plane surface lying in the rocking plane and its edge tangent to the axis of oscillation, there are provided two grinding diamonds for the useful portions of the grinding wheel. The first diamond has its cutting edge constantly lying in the rocking plane and it may thus completely grind the plane surface of the grinding wheel while the second diamond follows a, path adapted to give the edge of the grinding wheel the desired shape for grinding the connecting curve or cavetto connecting the side of the tooth with its bottom. The latter diamond may be brought into contact with the grinding wheel preferably along the edge of the latter which is tangent to the rocking shaft.

When the grinding wheel shows traces of wear, it is possible by means of adjusting devices for the grinding wheel carrier to cause the latter to move slightly beyond the desired position i. e. to make it project slightly beyond the rocking plane and laterally with reference to the rocking shaft. The action of the diamonds produces on one hand, a plane surface for the grinding wheel which surface lies exactly in coincidence with the desired plane while on the other hand it provides a suitably shaped edge tangent to the rocking axis.

The following description and corresponding accompanying drawings, given solely by way of examples and by no means in a limitative sense, show the manner in which the invention may be performed. The features appearing both in the drawings and in the specification form of course part of said invention.

Fig. 1 is a general diagram illustrating the principle of the grinding method according to my invention.

Fig. 2 is a perspective view with parts torn oif,

3 of a grinding machine to which the principle of my invention is applied.

Fig. 3 is a transversal cross-section and Fig. 4 is a plan view of the same.

Fig. 5 is a detailed cross-section through V-V of Fig. 3.

Fig. 6 is a vertical cross-section of the interconnecting member associating the rocking movements.

Fig. 7 is a plan view thereof.

Lastly Figs. 8 and 9 are perspective views of detail parts of said interconnecting member.

In the diagram shown in Fig. 1, the plane rocking round the axis X-X contains the cutting edge of the grinding wheel M and the rectilinear cam follower or ruler R. The edge of the latter is constrained through the agency of the-spring S to remain tangent to the side of the cam-C which is frusto-conical and is rigid with a pendulum P rotating round the axis YY which meets X X' at 0 and is' perpendicular thereto. The tooth D to be gr'oundis also carried by the pendulum P and is constrained to follow the movements of the latter rigidly. When'the plane 77 rocks in the direction of the arrow at, the pendulum P rocks in the direction of the arrow b. During this movement, the plane 'rr forms the envelope of the cone the'apex of which is at 0 and the base of which is formed by the cam C while the generating lines of this cone enter all in succession the plane. In the figure, the generating line G lies in this plane and its segment AB fOrIIling part of the tooth D is in contact with the grinding wheel M. Therefore if the grinding wheel M is submitted at the same time to a translational movement with reference to the tooth D, the entire side of the latter is enveloped by the cutting edge of the grinding wheel and is ground to the outline of the cam C. It is apparent moreover that if the edge of the grinding wheel is tangent to the'axis X-X and is given a suitable shape, this edg'ewill be adapted to produce the connecting cavetto between the circle at the bottom of the tooth of the gear and the flange of said tooth, which operation is of particular interest for increasing the resistance of the tooth.

The machine illustrated as a whole in Figures 2, 3 and 4 is adapted to execute automatically these different movements. In this" example of the execution, the axis X-X' which forms the eneral axis of the machine is vertical and the axis Y-Y' is horizontal.

The machine comprises a puppet l, carrying the gear 29 and the incline of which with reference to the axis XX' is adjustable througha sliding motion over the circular sector 2 having its center at 0 so that the generating lines of the cone connecting 0 with the bottom of the teeth of the gear 29 may occupy a vertical position. The puppet I includes chiefly a dividing mechanism of any known type actuated for instance by the cylinder 3 which may be hydraulic or pneumatic. The system comprising the puppet I and the sector 2 rocks round the axis YY inside a bearing 4 carried by the bracket 30. The bearing surfaces of this bearing 4 are formed by frusto-conical elements 3| shaped substantially after the manner of a horse shoe. The bearing 4 includes two portions 411 and 46 connected through the screws 32.

Inside the inner recess of the bearing 4' is secured the circular segment {through the agency of the screws 2a.

The rocking movement round the" Y-Y is transmitted to this bearing through the bar 5 a portion of which is shown in Fig. 2, and through the agency of the carriage 6 described hereinafter. The system including the bearing 4, the puppet I, the bar 5 and the carriage 6 forms the pendulumP of Fig. l.

The bracket 30 is rigid with a carriage 1 and is adapted to slide along the column 8 forming part of the casing. A reciprocating upward and downward movement may be transmitted to the carriage I, said movement being controlled for instance by a hydraulic mechanism shown diagrammatically at 10, the carriage being balanced by a mechanism 9 such as a counterweight inserted in the column, The carriage 1 is rigid at its lower part with a bracket 33 to which is secured the guiding member 34 bearing the carriage 6 forming the end of the bar 5. The details of this mounting are illustrated in Figs. 6 and 7, while Figs. 8 and 9 are perspective views showing the shape of the lower elements. The carriage 6 shown in Fig. 8 includes slideways 35 cooperating with slideways 36' on the guiding member 34 shown in Fig. 6, the common center for these slideways lying on the axis YY'. This carriage is moreover provided with cylindrical re- On the other hand'the guiding member 34 m cludes a bearing ll arranged centrally of the axis XX and wherein a shaft I2 is adapted to pivot. Said shaft l 2 is rigid at its'upper end with a plate 15 sliding between the rollers [7' (Fig. 5) in order to allow the relative vertical translational movement of the grinding wheelzl' with reference to the teeth of the gear wheel29, said translational movement being provided by the movement of the carriage 1; These rollers H are borne by the carriage l8 forming part of the grinding wheel frame 4| provided with the grinding wheel 2| the position of whichis adjusted by means of the handwheels 23' and 24. The car riage lB is circular and it rotates round theaxis XX' while rolling through the agency of a ball bearing l8a. over the stationary frame |9 of the machine; its rocking motion round the axis XX' is controlled by the motor 20 through the connecting rod 42 pivotally secured at 43 to the carriage I8.

The rocking movement of the carriage I 8" is transmitted by the plate IE to the shaft H the lower end ofwhich includes the ruler l3. This ruler and the vertical axis XX' define the plane 1;- containing the cutting edge of the grinding wheel. The rocking mountin of the ruler i3 is apparent in Figs. 6 and '7.

The shaft I2 is flutingly fitted inside a sleeve 44 carrying lateral extensions 45 inside which are rotatively carried the rollers 46. The lower end of the sleeve 44 is provided with two bearings 41 carrying the terminal pivots 48 of the rectilinear cam follower or r'uler iii; the medial line of the plane I31; providing for the contact of this ruler passes through the axis of the pivots 48. This arrangement allows doing away with the use of a cam 14 of frusto -conical shape which is difficult to machine, as a bearing for the'ruler I3. The ruler I3 is constantly urged against the side of the cam l4 through the action of the against one of the IOIIBIS 4t.

As apparent in Figs. '2, 3 and 4, the machine is completed by a first diamond 50 carried by a support so as to remain constantly in the plane of the feeler or ruler l3 and by a second diamond 52 the mounting of which is not illustrated and may be carried either by the vertical carriage I or by the frame 4| carrying the grinding wheel so as to provide through the lowering of the carriage 1 for the truing of the edge of the grinding Wheel 2|. It is thus possible to cut the edge of the grinding wheel sothat it may be tangent with the axis XX and assume the desired shape for producing the grinding of the cavetto connecting the teeth.

Finally the machine is carried by a base 53 subdivided into two inner compartments of which the former 54 is the larger and is adapted to contain the water for cooling the grinding wheel while the second compartment 55 contains oil. A pump 26 sucks this oil out of 55 for hydraulically controlling the dividing mechanism of the puppet I, and the vertical movements of the carriage I.

The diagram of Fig. 1 allows the operation of the machine to be easily understood. The motor 20 provides for the rocking movement of the carriage I8 i. e. in practice for that of the grinding wheel 2| and, through the agency of the plate I6 and of the shaft [2, that of the ruler I3. The spring l5 urges constantly the ground surface of this ruler against the cam l4 so that the carriage 6 receives a rocking movement the period of which is equal to that of the carriage l8, said movement being transmitted to the puppet I through the agency of the bar 5 and of the bearing 4.

When the dividing mechanism brings in succession the teeth into contact with the cutting surface of the grinding wheel the slides corresponding to a same side of the teeth are ground in succession.

For the grinding of the other side of the teeth it is sufficient to make the ruler I3 rotate inside the bearings 41 and engage the other side of the cam while the other roller 46 of the sleeve 44 is acted upon by the spring l5 which is then dismantled on the right hand side of Fig. 6 and reinserted in the recess 31 on the left hand side thereof. This operation is made easier by the dismantling of the plate 39 which is reinserted in a suitable position so that the cam l4 may lie on the other side of the ruler.

In order to make up for the wear of the grinding wheel, the latter is periodically trued through the diamonds 50 and 52.

By acting on the handwheel 24, the grinding wheel is first brought to project slightly beyond the plane 1r defined by the axis X-X' and the ruler I3; the sweeping of the surface of the grinding wheel by the diamond 5!] makes the cutting surface even and returns it exactly into the above plane. The operation begins over again with the handwheel 23 and the diamond 52 for bringing the edge of the grinding wheel into tangency with the axis X-X' and giving it the required shape. This operation of truing the grinding wheel should be begun over again periodically and as often as may be required.

Water taken out of the compartment 54 is used for wetting the grinding wheel. This water is again collected after use through the funnel shaped upper part of the carriage l8; it returns then into the bottom of the frame of the machine out of which it may again be removed if required.

Obviously many detail modifications may be brought to the machine and to the method described hereinabove in particular by using technically equivalent means for its various parts or steps without widening thereby the scope of my invention as defined in accompanying claims.

What I claim is:

1. A machine for grinding bevel gears comprising a grinding tool the cutting edge of which lies substantially tangent to an axis in the plane of said tool, a carrier for the tool adapted to rotate round said axis, a support adapted to rotate round an axis perpendicular to the first axis and meeting the same, a carrier for the gear to be ground mounted on said support, a cam carried by said same support in a position such that its outline lies on the cone the apex of which coincides with the meeting point of the axes and the generating lines of which are defined by the desired generating lines of the tooth to be ground, a rectilinear cam follower the operative plane of which contains the first axis, and means urging said follower against the cam whereby the rocking of the grinding wheel and cam follower system round the first axis provides for the simultaneous rocking of the cam support round the second axis.

2. A machine for grinding bevel gears comprising a grinding wheel the cutting edge of which lies substantially tangent to an axis in the plane of said wheel, a carrier for the Wheel adapted to rotate round said axis, a support adapted to rotate round an axis perpendicular to the first axis and meeting the same, a carrier for the gear to be ground mounted on said support, a cam carried by said same support in a position such that its outline lies on the cone the apex of which coincides with the meeting point of the axes, and the generating lines of which are defined by the desired generating lines of the tooth to be ground, a rectilinear cam follower the operative plane of which contains the first axis, means urging said follower against the cam whereby the rocking of the grinding wheel and cam follower system round the first axis provides for the simultaneous rocking of the cam support round the second axis and two cutters adapted to grind the grinding wheels when desired respectively over the surface thereof lying in the plane of the first axis and along the edge thereof lying tangent to said axis.

3. A machine for grinding bevel gears comprising a grinding tool the cutting edge of which lies substantially tangent to an axis in the plane of said tool, a carrier for the tool adapted to rotate round said axis, a support adapted to rotate round an axis perpendicular to the first axis and meeting the same, a puppet on said support, a dividing mechanism cooperating with the puppet, means whereby the puppet carries the gear to be ground with its axis lying in the plane of the two axes and passing through the meeting point thereof, means for adjusting the angular setting of the gear axis with reference to the two former axes, a cam carried by said same support in a position such that its outline lies on the cone the apex of which coincides with the meeting point of the axes, and the generating lines of which are defined by the desired generating lines of the tooth to be ground, a rectilinear cam follower the operative plane of which intersects the first axis and means urging said follower against the cam whereby the rocking of the grinding wheel and cam follower system round the first axis provides for the simultaneous rocking of the cam support round the second axis.

4. A machineifor grinding bevel gears comprising a grinding tool the cutting edge-of which lies substantially tangent to an axis in the plane of said tool, a carrier for the tool adaptedto, rotate round said axis, a support adapted to rotate round an axis perpendciular to the'first axis and meeting the same, a puppet on said support, a dividing mechanism cooperating with the puppet, means whereby the puppet carries the gear to be ground with its axis lying in the plane of the two axes and passing through the meeting point thereof, means for adjusting the angular setting of the gear axis with reference to the two former axes, a carriage for the puppet support adapted to slide in a direction parallel to the first axis, a cam carried by said same support in a position such that its outline lies on the cone the apex of which coincides with the meeting point of the axes, and the generating lines of which are defined by the desired generating lines of the tooth to be ground, a rectilinear cam follower the operative plane of which inersects the first axis, and means urging said follower against the cam whereby the rockin of the grindign wheel and cam follower system round the firstaxis provides for the simultaneous rocking of the cam support round the second axis.

5. A machine for grinding bevel gears com prising a grinding tool the cutting edge of which liessubstantially tangent to "an axis in the plane of said tool, a carrier for the tool adapted to rotate round said axis, a support adapted to rotate round an axis perpendicular to the first axis and meeting the same, a carrier for the gear to be ground mounted on said support, a cam carried by said same support in a position such that its outline lies on the cone the apex of which coin,- cides with the meeting point of the axes, and the generating lines of which are defined by the desired generating lines of the tooth to be ground, cooperating arcua'te slideways on the gear carrier support and on the tool carrier the center of which coincides with the meeting point of the axes, a rectilinear cam follower the operative plane of which intersects the first axis, and means urging said follower against the cam whereby the rocking of the grinding wheel and cam follower system round the first axis provides for the simultaneous rocking. of the cam support round the second axis.

6. A machine for grinding bevel gears comprising a grinding tool the cutting edge of which lies substantially tangent to anaxis in the plane of said tool, a carrier for the tool adapted to rotate round said axis, a support adapted to rotate round an axis perpendicular to the first axis and meeting the same, a carrier for the gear to be ground mounted on said support, a cam carried by said same support in a position such that its outline lies on the cone the apex of which coincides with the meeting point of the axes and the generating lines of which are defined by the desired generating lines of the tooth to be ground, cooperating arcuate slideways on the gear carrier support and on the tool carrier the center of which coincides with the meeting point of the axes, a rectilinear cam follower the operative plane of which intersects the first :axis, a pivoting axis for the cam follower lying in its operative plane, means whereby the cam is adapted to cooperate with the cam follower in two opposite relative positions according to the position assumed by the cam follower to either side of :its pivotal axis, and means urging said follower against the cam whereby the rocking of the grinding wheel and cam follower system round the first axis provides for the simultaneousrocln ing of, the cam support round the second axis.

7. iA-machine for grinding bevel gears-comprising a grinding-tool the cutting edge of which lies substantially tangent to an axis in the plane of said tool, a carrier for the tool adapted to rotate round said axis, a support adapted to rotate round-an axis perpendicular to the first axis and meeting the same, a carrier for the gear to be ground mounted on said support, a cam carried by said same support in a position such that its outline lies on the cone the apex of which coincides with the meeting point of the axes and the generating lines of which are defined by the desired generating lines of the tooth to be ground, an extension for the tool carrier adapted to slide over the latter in parallelism with the first axis, a slideway parallel to said first axis for the tool carrier, cooperating arcuate slideways on the extension and on the tool carrier, the center of which lies on said first axis, a rectilinear cam follower the operative plane of which intersects the first axis, and means urging said follower against the cam whereby the rocking of the grinding wheel and cam follower system round the first axis provides for the simultaneous rocking of the cam support round the second axis.

8. A machine for grinding bevel gears comprising a tool support adapted to rotate round a first axis, a grinding tool carried in a radial plane thereof with its cutting edge tangent to said first axis, a support adapted to slide in parallelism with said first axis, a gear carrier adapted to rotate with reference to said support round an axis perpendicular to and intersecting the first axis, an extension for the tool support adapted to slide with reference thereto in parallelism with the first axis and rotatively engaging the sliding support, a cylindrical cam removably secured to the sliding support in a position such that it forms with the intersection of the two axes a cone defining the shape of the tooth to be ground, a rectilinear cam follower rotatively carried by the extension of the tool support with its operative surface flush with said first rotary axis and elastic means urging the cam follower against the cam.

9. A machine for grinding bevel gears comprising a tool support adapted to rotate round a first axis, a grinding tool carried in a radial plane thereof with its cutting edge tangent to said first axis, a support adapted to slide in parallelism with said first axis, a gear carrier adapted to rotate with reference to said support round an axis perpendicular to and intersecting the first axis, an extension for the tool support adapted to slide with reference thereto in parallelism with the first axis, an arcuate guideway pivotally secured to the extension for the tool support coaxially with the first axis and the center of which is on said first axis, a cooperating guideway on the sliding support, a cylindrical cam removably secured to the sliding support in aposition such that it forms with the intersection of the two axes a cone defining the shape of the tooth to be ground, a rectilinear cam follower rotatively carried by the extension of the tool support with its operative surface flush with said first rotary axis and elastic means urging the cam follower against the cam.

10. A machine for grinding bevel gears comprising a tool support adapted to rotate round afirst axis, a grinding tool carried in a radial plane thereof with its cutting edge tangent to said: first axis, a support adapted to slide in parallelism with said first axis, a gear carrier adapted to rotate with reference to said support round an axis perpendicular to and intersecting the first axis, an extension for the tool support adapted to slide with reference thereto in parallelism with the first axis, and rotatively engaging the sliding support, a cylindrical cam removably secured to the sliding support in a position such that it forms with the intersection of the two axes a cone defining the shape of the tooth to be ground, a hearing pivotally mounted on the extension of the tool support coaxially with reference thereto, and carrying said cam follower with its operative surface flush with said first rotary axis and elastic means urging the cam follower against the cam.

MAURICE JOSEPH SUIRE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 1,058,353 Cookingham et al. Apr. 8, 1913 1,811,254 Bayley June 23, 1931 2,342,129 Elbertz Feb. 22, 1944 

